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RE: [TCML] Questions on grounding

Hello Joe,
The reason that a fan on the spark gap helps improve output of a Tesla coil is that it helps to extinguish the arc and blow out the ions. When the ions are all gone, the gap takes a higher voltage to make it break down, which means that there's more 'bang energy', resulting in more energy transferred to the secondary coil and that means larger streamers on the output.

> From: jocatch@xxxxxxxxxxx
> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] Questions on grounding
> Date: Wed, 15 Apr 2009 14:01:07 -0400
> CC: 
> Hello to everyone who has responded so far. Thank you!
> Today I went and got a 4' ground rod and banged it into the ground and ran a 
> wire to the secondary coil and nst case. I used a 4' rod because my ground 
> here has lots of rocks and I have never been able to go more than about 4' 
> with ground rods. As you can see from my photos that the coil is on my rear 
> deck, there is no concrete floor. The wire from the coil to the rod is less 
> than 20' long. Tonight after dark I will power it up and see if it helped. I 
> will also connect the ground wire to the end of a pole and see how long of a 
> spark I can get.
> Regarding my spark gap, I always go for the easiest, simplest solution as I 
> am not that mechanically inclined. I do have some 12v computer fans I was 
> thinking about placing near the gap to see if it helps. But I wanted to try 
> the grounding, tuning and adjusting the gap width before adding a fan. 
> Besides, I have no place right now to add the fan on the base; I will have 
> to move the gap to somewhere where there is more room. Regarding a 'sucker' 
> gap, I am not sure what that is, I will have to research that.
> Joe
> ----- Original Message ----- 
> From: "Lau, Gary" <Gary.Lau@xxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Wednesday, April 15, 2009 10:36 AM
> Subject: RE: [TCML] Questions on grounding
> Hi Joe,
> When you say that "Right now, nothing is grounded to earth or electrical 
> ground", this is REALLY bad!  The secondary base needs a ground connection. 
> If there is not a good, direct ground connection, the RF current will travel 
> through your hot & neutral wires and wreak havoc with household appliances.
> I agree with Bart's reply - that the secondary base is typically connected 
> to the NST case, and that this case connection should go to a dedicated RF 
> ground, not the mains ground.  For low powered coils, the mains ground is 
> often used, but the definition of "low" is subjective.
> Regarding the sparks discharging all around the toroid, this may be due to 
> having a ragged surface on the toroid, so smoothing it out may help.  If the 
> toroid is simply too small for the power level you're running at, no amount 
> of surface prep is going to help, but yours appears to be reasonable in 
> size.
> Looking at your web site, I think the weak link in your coil is the 2 
> carriage bolt spark gap.  It needs forced air flow directly through the arc 
> (more than just a gentle breeze from a fan), and should be designed to arc 
> not at just a single point as yours will.  I recommend using a sucker gap, 
> as it's easy to build and works very well.
> Regards, Gary Lau
>> -----Original Message-----
>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
>> Behalf Of jocatch
>> Sent: Tuesday, April 14, 2009 9:35 AM
>> To: tesla@xxxxxxxxxx
>> Subject: [TCML] Questions on grounding
>> Hello. I have built my first coil using standard parts and dimensions and 
>> have fired it
>> up and so far I am producing sparks but only about 12" long. I am using a 
>> 12KV nst
>> with .0125uf mmf, 13 turns of copper tubing as primary and 20" of #28 
>> magnet wire
>> on a 4" form with aluminum cloths dryer ducting for the toroid
>> My questions concerning grounding. I have read alot about discharge spark 
>> length
>> but not much regarding how to measure it. Above I said 12" discharge spark 
>> length,
>> that was to a key ring held at the end of a boom stick handle. Should the 
>> metal
>> object that I am drawing the spark to be grounded? To earth ground? Right 
>> now
>> nothing is grounded to earth or electrical ground. The bottom side of the 
>> secondary
>> coil is connected to the metal case of the nst. Should the secondary coil 
>> and nst be
>> grounded to earth ground?
>> Lastly, the aluminum toroid is discharging all around its circumference. I 
>> know the
>> fewer discharge points on the top load, the bigger the discharge length 
>> will be. If I
>> tape the toroid with aluminum tape to produce a smoother surface, will it 
>> help?
>> I have a web page showing photos of my first tesla coil before I recently 
>> updated it
>> to copper tubing and new toriod. The web page shows the old primary wire 
>> coil and
>> old topload. I will post new pictures of the update soon.
>> http://www.joecool.org/joe_s_tesla_coil.htm
>> Thanks for your help.
>> joe
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